First thing to check is the web page itself. If you see a "Print this page" or "Printable version" link or button, click on it. That's the best option of all!

Some, but not all web pages can be 'fixed' by dragging the browser window to a narrower size, and then clicking on 'refresh' before printing off.

When all else fails, 'Landscape' mode is best. Choose 'File -> Print' and then click on 'Printer Preferences -> Page Layout' (or whatever is there for your printer) and choose 'Landscape Mode' instead of 'Portrait Mode'. Just make the change and click 'OK' to continue. If yopu click on 'Apply' you'll end up changing the default settings for your printer!